Q: Tunisian Collaborative Painting

I found the Tunisian collaborative paintings to be very interesting. Many of them turn out to be abstract, and imaginative rather than realistic and observational. What I do find strange is the fact that these paintings end up being in the same style. I would expect for certain areas to have different styles because of the large amount of people working on them. I wondered if the artists all agreed to leveling out the style once they were finished with the painting, or if the painting just turned out to be uniform. I would have also expected there to be a wide range of subjects included in the painting, but these paintings all have one subjects. Maybe the artists agreed on the subject, and experimented with the rest of the painting? Maybe they started with one idea and worked around it? Who knows.